Done my alternator build but ran in different drama's lol. The Banzai Racing Dual Belt Alternator Pulley Kit 79-91 RX-7 FB FC. Is correct but i thought the FD alternator where the same. But nah alternator shaft diameter is not the same and your missing the bushing spacer in that particular kit. I machine the pulley and make it to fit.

I installed this fd alternator work fine but it was an struggle to make the excisting charge light to turn off. I try many ways but ended buring the alternator. I,ll check another alternator and then update this again.... car not move for 4 months now